It is desirable to develop a driving assistance device which enables a driver to easily operate vehicle driving assistance and which is easy to manipulate for a case in which a vehicle travels and an emergency occurs, such as a case in which it is difficult to drive because a driver suddenly feels ill and the driver wants to stop the vehicle or a case in which it is temporarily difficult to drive because, for example, the driver sneezes and the driver wants to temporarily drive the vehicle along a road.
Here, as a device which performs host vehicle driving assistance, a travel assistance system has been known which can perform travel assistance control for constant speed travel, travel in a traffic jam, or the like, as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2001-260704. A travel assistance system includes an ACC (Active Cruise Control) microcomputer, a travel control microcomputer for traffic jams, a system operating switch, a SET switch, a CANCEL switch, and vehicle speed detection means.
In such a travel assistance system, the system operating switch, the SET switch, and the CANCEL switch are used for both the ACC microcomputer and the travel control microcomputer for traffic jams. For example, the system operating switch, the SET switch, and the CANCEL switch function as the control switches of the ACC microcomputer in a case in which vehicle speed is equal to or greater than 35 km/h and as the control switches of the travel control microcomputer for traffic jams in a case in which vehicle speed is equal to or less than 20 km/h, and travel assistance control can be realized based on the traveling state of a vehicle.